I have a desktop running 8.04 LTS. It is set to show only LTS upgrades so I would think it should now be prompting for me to upgrade. But it isn't. If I change it to prompting for any upgrade it prompts to upgrade to 8.10. But changing it back to only prompting for LTS versions again leaves it not prompting for anything. Any ideas why that would be?

If it matters the machine did run 6.06 LTS a long time ago until I moved it to 8.04.